1. Technical Field
The present invention relates to a printing control apparatus and a printing control method.
2. Related Art
An ink jet printer is known which performs printing by discharging ink to a printing medium using a printing head which includes nozzle rows in which a plurality of nozzles capable of discharging the ink are arranged in a nozzle row direction. In the ink jet printer, a platen gap (hereinafter, PG) which is a distance from a platen supporting the printing medium on which the ink is discharged to the printing head is varied according to differences of the printing medium being used, or the like.
In addition, in the ink jet printer, when discharging the ink from the nozzles, together with discharged ink droplets (the main droplets), droplets which are so-called satellites, or the like, which are fine compared to the main droplets are discharged. The satellites are referred to as sub-droplets. In addition, a part of the main droplets which are discharged and flown is scattered and becomes the sub-droplets.
Also, a recording operation is known in which one ink droplet is ejected from the nozzle when a distance from a nozzle formed surface of a recording head to a recording medium is relatively short (for example, 1 mm or less), two ink droplets are continuously ejected from the nozzle (two ink droplets are combined and flown before reaching recording medium) when the distance is relatively long (for example, 2 mm or more), four ink droplets are continuously ejected from the nozzle (four ink droplets are combined and flown before reaching recording medium) when the distance is longer (for example, 3 mm or more) (refer to JP-A-2014-148110).
When the sub-droplets are combined with the main droplets in the air until being landed onto the printing medium, or a landed position thereof is within a range in which the main droplets are landed and formed, the sub-droplets are not actually seen in a printing result. Meanwhile, when the sub-droplets are deviated from the main droplets and landed onto the printing medium, the sub-droplets are preset in the printing result so that the image quality is deteriorated. Particularly, when the sub-droplets are generated at the time of printing letters or ruled lines, the letters or ruled lines are blurred such as giving an observer the impression of seeing double. Moreover, hereinafter, “generation” of the sub-droplets means a state in which the sub-droplets are present on the printing medium deviated from the main droplets.
The PG is correlated with the generation of the sub-droplets. An orbital of the sub-droplets, which are smaller and lighter than the main droplets, is likely to be scattered during flying, due to air resistance or the influence of air current. Accordingly, the sub-droplets are capable of being deviated from the main droplets to be followed, as much as flying time is long. As much as the PG is wide, the flying time of the ink discharged is likely to be long. For this reason, as much as the PG is wide, the sub-droplets are likely to be generated. Accordingly, measures for suppressing the deterioration of the image quality due to the sub-droplets, which are likely to be generated according to the PG, are required.